This invention relates to a system for the compliant suspension of an instrumentation package at some predetermined ocean depth from a buoy, and more particularly to a system for isolating the instrument package from wave motion of the buoy while the package is suspended from the buoy at a predetermined depth by a cable payed out from a pack attached to the submerged instrument package.
In underwater instrumentation packages, such as in a hydrophone installation for sonobuoys, it is desirable to have the transducer suspended in a stable position at a predetermined depth below the ocean surface. This is because the instrumentation package serves as a platform for the transducers which, as in the case of a hydrophone, may be sensitive to vertical motion imparted through the suspension cable by surface waves acting on the buoy. To achieve stability, motion damper assemblies have been developed, in addition to specialized configurations in buoy systems. A typical prior-art motion damper uses a low spring-rate elastomeric rod as a link in the suspension cable, as shown in U.S. Pat. Nos. 3,377,615 and 3,543,228. Since the suspension cable also serves as a communication cable, and insulated signal wire loosely wound around the elastomeric rod electrically connects the ends of the inner conductors of the suspension cables otherwise linked only by the elastomeric rod. A problem with the elastomeric rod as a compliant link is that the length and bulk of the compliant rod becomes prohibitive for the terminal mass (mostly coupled water mass) attached below the link because of the very low spring rate required for wave-induced motion.